Wideband Polar Receiver Architecture and Signal Processing Methods

1. A method comprising: receiving a phase-modulated input signal at a polar receiver including an injection locked oscillator, wherein the injection-locked oscillator includes at least a first set of injection points and a second set of injection points, each set of injection points corresponding to a different harmonic of the injection-locked oscillator; based on a frequency of the input signal, selecting one of a plurality of band-specific amplifiers; amplifying the input signal with the selected one of the band-specific amplifiers; based on the frequency of the input signal, selecting one of the sets of injection points; operating the injection-locked oscillator to generate an oscillator output signal while injecting the input signal at the selected set of injection points; and measuring a phase of the oscillator output signal.

2. The method of claim 1 , wherein selecting one of the sets of injection points includes: based on the frequency of the input signal, selecting an Nth harmonic of the injection-locked oscillator such that the frequency of the input signal divided by N is within a locking range of the injection-locked oscillator; and selecting a set of injection points associated with the Nth harmonic of the injection-locked oscillator.

3. The method of claim 2 , wherein a set of injection points associated with the second harmonic consists of two injection points, and wherein a set of injection points associated with the fourth harmonic consists of four injection points.

4. The method of claim 2 , further comprising tuning the injection-locked oscillator such that a free-running frequency of the injection-locked oscillator is substantially the frequency of the input signal divided by N.

5. The method of claim 1 , wherein the injection-locked oscillator is a ring oscillator including a plurality of sequential buffers, and wherein each of the injection points is at a respective buffer.

6. The method of claim 5 , wherein injecting a signal at an injection point includes modulating a current source supplying the respective buffer.

7. The method of claim 5 , wherein each of the buffers introduces a buffer phase shift, and wherein a set of injection points associated with a second harmonic includes at least two differential injection points separated by a total buffer phase shift of substantially 90°.

8. The method of claim 5 , wherein each of the buffers introduces a buffer phase shift, and wherein a set of injection points associated with a fourth harmonic includes at least two differential injection points separated by a total buffer phase shift of substantially 45°.

9. The method of claim 5 , wherein the ring oscillator includes four buffers, and wherein: a first set of injection points consists of respective injection points at a first, second, third and fourth one of the buffers; and a second set of injection points consists of respective injection points at a second and a fourth one of the buffers.

10. A polar receiver for measuring the phase of a phase-modulated RF input signal, the receiver comprising: a plurality of band-specific amplifiers, each amplifier configured to amplify RF signals in a respective predetermine frequency band; an injection-locked oscillator including at least a first set of injection points and a second set of injection points, each set of injection points corresponding to a different harmonic of the injection-locked oscillator, the injection-locked oscillator further having an oscillator output; injection selection circuitry operative to selectively provide the input signal from a selected amplifier of the plurality of band-specific amplifiers to a selected one of the sets of injection points; and phase detection circuitry connected to the oscillator output.

11. The receiver of claim 10 , wherein the phase detection circuitry comprises: a frequency divider having an input connected to the oscillator output, the frequency divider further having a frequency-divided output; and a time-to-digital converter connected to the frequency-divided output.

12. The receiver of claim 10 , wherein the injection-locked oscillator is a ring oscillator.

13. The receiver of claim 12 , wherein the ring oscillator includes four buffers, and wherein: a first set of injection points consists of respective injection points at a first, second, third and fourth one of the buffers; and a second set of injection points consists of respective injection points at a second and a fourth one of the buffers.

14. The receiver of claim 10 , wherein the injection-locked oscillator is tunable.

15. The receiver of claim 10 , wherein the injection-locked oscillator is a ring oscillator comprising a plurality of sequential buffers, each buffer having a corresponding current source, and wherein each injection point is operative to modulate a respective one of the current sources.

16. The receiver of claim 15 , wherein each of the buffers introduces a buffer phase shift, and wherein a set of injection points associated with a second harmonic includes at least two differential injection points separated by a total buffer phase shift of substantially 90°.

17. The receiver of claim 15 , wherein each of the buffers introduces a buffer phase shift, and wherein a set of injection points associated with a fourth harmonic includes at least two differential injection points separated by a total buffer phase shift of substantially 45°.

18. The receiver of claim 10 , further comprising controller logic operative to perform functions including: in response to a selection of an input signal frequency, selecting an Nth harmonic of the injection-locked oscillator such that the input signal frequency divided by N is within a locking range of the injection-locked oscillator; and controlling the injection selection circuitry to provide the input signal to a set of injection points corresponding to the Nth harmonic.

19. A method, comprising: receiving a phase-modulated input signal at an injection locked ring oscillator having a plurality of sequential buffers and at least a first set of injection points and a second set of injection points, each set of injection points corresponding to a different harmonic of the injection-locked oscillator; selecting one of the sets of injection points based on a frequency of the input signal; injecting the input signal at the selected set of injection points of the injection-locked oscillator to generate an oscillator output signal by modulating a current source supplying the respective buffer; and measuring a phase of the oscillator output signal.

20. The method of claim 19 , wherein selecting one of the sets of injection points includes: based on the frequency of the input signal, selecting an Nth harmonic of the injection-locked oscillator such that the frequency of the input signal divided by N is within a locking range of the injection-locked oscillator; and selecting a set of injection points associated with the Nth harmonic of the injection-locked oscillator.

21. The method of claim 20 , wherein a set of injection points associated with the second harmonic consists of two injection points, and wherein a set of injection points associated with the fourth harmonic consists of four injection points.

22. The method of claim 20 , further comprising tuning the injection-locked oscillator such that a free-running frequency of the injection-locked oscillator is substantially the frequency of the input signal divided by N.

23. The method of claim 19 , wherein each of the buffers introduces a buffer phase shift, and wherein a set of injection points associated with a second harmonic includes at least two differential injection points separated by a total buffer phase shift of substantially 90°.

24. The method of claim 19 , wherein the ring oscillator includes four buffers, and wherein: a first set of injection points consists of respective injection points at a first, second, third and fourth one of the buffers; and a second set of injection points consists of respective injection points at a second and a fourth one of the buffers.

25. An apparatus, comprising: an injection-locked ring oscillator comprising a plurality of serially connected buffers, each buffer having a corresponding current source, and at least a first set of injection points and a second set of injection points, each set of injection points being operative to modulate a respective one of the current sources and each set of injection points corresponding to a different harmonic of the injection-locked oscillator, the injection-locked oscillator further having an oscillator output; injection selection circuitry operative to selectively provide the input signal to a selected one of the sets of injection points; and phase detection circuitry connected to the oscillator output.

26. The receiver of claim 25 , wherein the phase detection circuitry comprises: a frequency divider having an input connected to the oscillator output, the frequency divider further having a frequency-divided output; and a time-to-digital converter connected to the frequency-divided output.

27. The receiver of claim 25 , wherein the ring oscillator includes four buffers, and wherein: a first set of injection points consists of respective injection points at a first, second, third and fourth one of the buffers; and a second set of injection points consists of respective injection points at a second and a fourth one of the buffers.

28. The receiver of claim 25 , wherein the injection-locked oscillator is a ring oscillator comprising a plurality of sequential buffers, each buffer having a corresponding current source, and wherein each injection point is operative to modulate a respective one of the current sources.

29. The receiver of claim 28 , wherein each of the buffers introduces a buffer phase shift, and wherein a set of injection points associated with a second harmonic includes at least two differential injection points separated by a total buffer phase shift of substantially 90°.

30. The receiver of claim 25 , further comprising controller logic operative to perform functions comprising: in response to a selection of an input signal frequency, selecting an Nth harmonic of the injection-locked oscillator such that the input signal frequency divided by N is within a locking range of the injection-locked oscillator; and controlling the injection selection circuitry to provide the input signal to a set of injection points corresponding to the Nth harmonic.